To learn about supported `cron` expression formats and aliases, see [Cron expression formats](#cron-expression-formats) in this article.

* [Cron expression formats](#cron-expression-formats)

A Cron expression represents a set of time fields through six space-separated fields. You can also use predefined schedules or fixed interval scheduling in place of Cron expressions.

The table below describes the fields you can define in a Cron expression.

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Field | Mandatory | Allowed values | Allowed special characters

|---------- | ---------- | -------------- | --------------------------|

Seconds | No | 0-59 | * / , -|

Minutes | Yes | 0-59 | * / , -|

Hours | Yes | 0-23 | * / , -|

Day of month | Yes | 1-31 | * / , - ?|

Month | Yes | 1-12 or JAN-DEC | * / , -|

Day of week | Yes | 0-6 or SUN-SAT | * / , - ?|

The table below describes the purpose of the special characters in a Cron expression.

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|Special Character | Description |

|---------- | ---------- |

|**Asterisk** (`*`) | Indicates that the Cron expression will match for all values of the field.<br>Using an asterisk in the 5th field (month), would indicate every month.|

|**Slash** (`/`) | Slashes are used to describe increments of ranges. <br>For example `3-59/15` in the 1st field (minutes) would indicate the 3rd minute of the hour and every 15 minutes thereafter. <br>The form `*\/...` is equivalent to the form `first-last/...`, that is, an increment over the largest possible range of the field. <br>The form `N/...` is accepted as meaning `N-MAX/...`, that is, starting at `N`, use the increment until the end of that specific range. It does not wrap around.|

|**Comma** (`,`) | Commas are used to separate items of a list. For example, using `MON,WED,FRI` in the 5th field (day of week) would mean Mondays, Wednesdays and Fridays.|

|**Hyphen** (`-`) | Hyphens are used to define ranges. For example, `9-17` would indicate every hour between 9am and 5pm inclusive.|

|**Question mark** (`?`) | Question marks can be used instead of asterisks (`*`) for leaving either day-of-month or day-of-week blank.|

You can use one of several predefined schedules instead of a Cron expression.

The table below describes the predefined schedules supported.

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|Predefined schedule | Description | Equivalent to|

|----- | ----------- | -------------|

|@yearly (or @annually) | Run once a year, midnight, Jan. 1st | 0 0 0 1 1 *|

|@monthly | Run once a month, midnight, first of month | 0 0 0 1 * *|

|@weekly | Run once a week, midnight on Sunday | 0 0 0 * * 0|

|@daily (or @midnight) | Run once a day, midnight | 0 0 0 * * *|

|@hourly | Run once an hour, beginning of hour | 0 0 * * * *|

You can also schedule a job to execute at fixed intervals by adding `@every <interval>`. The <interval> is a string that represents the desired frequency.

For example, `@every 1h30m10s` would indicate a schedule that triggers every 1 hour, 30 minutes, 10 seconds.

The interval does not take the runtime of the job into account. For example, if a job takes three minutes to run, and it is scheduled to run every five minutes, it will have only two minutes of idle time between each run.

To learn about supported `cron` expression formats and aliases, see [Cron expression formats](#cron-expression-formats) in this article.